This invention relates to a cassette loading mechanism for a magnetic recording and reproducing apparatus such as a video tape recorder. The cassette loading mechanism of the present invention is particularly suitable for a motor drive type cassette loader or so-called "front loading type cassette loader" which first moves horizontally a cassette holder for holding a cassette and then vertically such holder by use of the driving force of a motor.
Such a front loading type cassette holder (hereinafter called the "front loading mechanism") is constructed as shown in FIGS. 4 and 5 of the accompanying drawings.
FIG. 4 is a perspective view of a conventional front loading mechanism and FIG. 5 is its right side view.
As shown in these drawings, the front loading mechanism includes a cassette holder 12 between right and left side brackets 2 and 3, and the cassette holder 12 are supported by guide holes 2a, 2b and 3a, 3b formed on the right and left side brackets 2 and 3, respectively. Reference numeral 11 represents a motor for front loading only, and the driving force of the motor is transmitted to a gear 9 through a worm 10 which rotates integrally with the drive shaft of the motor 11, and further from gear 9 to a gear 8. A sheet-like projection member 13 having an elongated hole 13a is fixed to a rotary shaft of the gear 8, and a cassette holder support portion 12a penetrates through, and meshes with, this elongated hole 13a. The cassette holder support portion 12a penetrates through the guide hole 2a formed on the right side bracket 2. Another cassette holder support portion 12b is inserted through the guide hole 2a. Reference numeral 14 represents cassette guide frames that are fitted to the right and left brackets 2, 3.
Now, when the cassette 1 is fitted and loaded into the cassette holder 12 from a direction represented by an arrow in FIG. 4, a detection switch (not shown) is turned on by the movement of the cassette holder 12. In consequence, the motor 11 is actuated and its driving force is transmitted to the gear 8 through the worm 10 and the gears 9, 9'. When the gear 8 rotates clockwise, the sheet-like projection member 13 rotates in the same direction, too, whereby the cassette holder 12 receives the force in the right ward direction from the sheet-like projection member 13 and is conveyed horizontally to the inner part while holding the cassette 1 and being guided by the guide holes 2a, 2b and 3a, 3b. When the cassette holder 12 moves a predetermined distance in the horizontal direction, it is conveyed downwardly in the vertical direction while being guided by the vertical portions of the guide holes 2a, 2b and 3a, 3b.
When the cassette 1 is loaded to a predetermined position in the manner described above, a magnetic tape (not shown) stored in the cassette 1 is pulled out by a tape loading mechanism (not shown) of VTR (Video Tape Recorder) and is wound on a cylinder (not shown) supporting thereon recording and reproducing heads. Thereafter, recording and reproduction to and from the magnetic tape are made.
Since the front loading mechanism described above includes the motor 11 for front loading only, the mechanism is large in size and high in cost of production.
Therefore, a front loading mechanism which eliminates the driving source for front loading only and utilizes the power source (for example, a motor for driving capstans) of a magnetic recording and reproducing apparatus also for front loading has been proposed. However, the front loading mechanism of this type has the following problems.
First of all, when the driving force is transmitted to the front loading mechanism from the magnetic recording and reproducing apparatus, a rubber belt or gears are used as a power transmission member. In the case of the former, however, belt fitting work becomes necessary after the assembly of the front loading mechanism to the magnetic recording and reproducing apparatus, and this method is not very suitable for reducing the number of production steps and for easy service maintenance in the field.
In the case of the gears, the problem described immediately above does not exist, but deviation of the distance between shafts for the gears depends on accurate fitting. If setting of the distance between the gear shafts is not good, defective operation of the cassette and escape of the gear teeth will occur. Since the hands of people come into direct contact with the front loading mechanism, unexpectedly great force is likely to act upon the front loading mechanism, and for this reason, the accuracy of spacing must be secured. Furthermore, the gears must mesh correctly with one another at the time of the assembly of the front loading mechanism.
As a prior art reference relating to the apparatuses of this kind, mention can be made of Japanese Patent Laid-Open No. 171065/1984.